1. Field of the Invention
This invention relates generally to an apparatus and method for the treatment of the stomach. More specifically, the invention relates to an apparatus and method to reduce the distensibility and/or volume of the stomach to treat obesity and other eating disorder related conditions.
2. Description of Related Art
Currently, a large segment of the American population suffers from eating disorders which can cause obesity, bulimia and anorexia leading to a number of disease states both physical and psychological. Since the advent of processed foods with designer taste addition, obesity has become prevalent in every geographic area of the United States. The snack food slogan, xe2x80x9cyou cannot eat just onexe2x80x9d has become a reality. Modification of excessive dietary intake is a multibillion-dollar industry.
There are many severe health consequences of obesity including heart disease, stroke and diabetes all of which can result in death, morbidity and/or significant quality of life issues. Related health conditions include gastroesophageal reflux (GERD) which is caused from regurgitation of gastric contents into the esophagus is aggravated by excessive food intake typical of compulsive eating and other eating disorders associated with the obese patient. These contents are highly acidic and potentially injurious to the esophagus resulting in a number of possible complications of varying medical severity. The reported incidence of GERD in the U.S. is as high as 10% of the population. Acute symptoms of GERD include heartburn, pulmonary disorders and chest pain. On a chronic basis, GERD subjects the esophagus to ulcer formation, or esophagitis and may result in more severe complications including esophageal obstruction, significant blood loss and perforation of the esophagus. Severe esophageal ulcerations occur in 20-30% of patients over age 65.
Current medical management has not been able to successfully intervene to significantly reduce the incidence of obesity within the U.S. For example, pharmacological modification with diet suppressants has been associated with significant metabolic side effects. Various attempts to reduce the volume of the stomach through surgical intervention or indwelling devices have had limited effectiveness with significant drawbacks. For example, in the morbidly obese, surgical intervention with gastric stapling, gastric banding and ileo-jejunal bypass has been abandoned because of the severe short-term surgical complications and the long-term side effects of surgically induced malabsorption and/or the potential for gastric obstruction. Other attempts to reduce the volume of the stomach through the use of indwelling gastric balloons have had only limited effectiveness in combatting the dietary rages of these patients. Such devices are prone to failure due to the extremely corrosive /acidic environment of the stomach. Once placed, they can not be readily modified or adjusted to meet the changing eating patterns and dietary needs of the patient. Also, they fail to address the significant problem of injurious contact with the gastric mucosa that can result from leaving an inflated bag in the stomach for an extended period of time. Moreover, these devices and approaches present the potentially fatal risks of gastric obstruction and infection from the indwelling device. Finally, due to combination of one or more of gastric wall contact, gastric obstruction and bacterial infection, such devices present a significant risk of causing gastric ulcers.
The present therapies for GERD include pharmacological, surgical and minimally invasive treatment. Despite marginal success, all have clinical limitations and none adequately treat the disease or address the patient""s need to reduce ingested food. Current drug therapy for GERD includes histamine receptor blockers which reduce stomach acid secretion and other drugs which may completely block stomach acid. However, while drugs may provide short-term relief, they do not address the underlying cause of LES dysfunction. They also present the disadvantage of adverse side affects as well as requiring the patient to remain on long term drug therapy which is often cost prohibitive. Surgically invasive procedures requiring percutaneous introduction of instrumentation into the abdomen exist for the surgical correction of GERD. One such procedure, Nissen fundoplication, involves constructing a new xe2x80x9cvalvexe2x80x9d to support the LES by wrapping the gastric fundus around the lower esophagus. Although the operation has a high rate of success, it is an open abdominal procedure with the usual risks of abdominal surgery including: postoperative infection, herniation at the operative site, internal hemorrhage and perforation of the esophagus or of the cardia. A 10-year study reported the morbidity rate for this procedure to be 17% and mortality 1%. This rate of complication drives up both the medical cost and convalescence period for the procedure and excludes significant portions of certain patient populations (e.g., the elderly and immuno-compromised).
Efforts to perform Nissen fundoplication and related sphincteroplasty procedures by less invasive techniques have resulted in the development of laparoscopic Nissen fundoplication and related laparoscopic procedures. Other attempts to perform fundoplication involve fastening of the invaginated gastroesophageal junction to the fundus of the stomach via a transoral approach using a remotely operated fastening device, eliminating the need for an abdominal incision. However, this procedure is still traumatic to the LES and presents the postoperative risks of gastroesophageal leaks, infection and foreign body reaction, the latter two sequela resulting when foreign materials such as surgical staples are implanted in the body.
While the methods reported above are less invasive than an open Nissen fundoplication, some still involve making an incision into the abdomen and hence the increased morbidity and mortality risks and convalescence period associated with abdominal surgery. Others incur the increased risk of infection associated with placing foreign materials into the body. All involve trauma to the LES and the risk of leaks developing at the newly created gastroesophageal junction. Other noninvasive procedures for tightening the LES still do not solve the fundamental problem of reducing the patient""s ability to overeat and cause an overproduction of stomach acid which results in acid reflux. It is predicted that such a reduction can ameliorate gastroesophageal reflux without direct modification of the sphincter and the resulting complications.
In order to more fully appreciate the issue involved in the treatment of obesity and the diagnosis and treatment of obesity-related conditions a description of the anatomy of the stomach and adjoining structures will now be presented. Referring to FIGS. 1A and 1B, the anatomy of the stomach can be divided into different segments on the basis of the mucosal cell types in relation to external anatomical boundaries. The cardiac segment is immediately subjacent to the gastroesophageal junction and is a transition zone of the esophageal squamous epithelium into the gastric mucosa. The fundus is the portion of the stomach that extends above the gastroesophageal junction. The body or corpus of the stomach extends from the fundus to the incisura angularis on the lesser curvature of the stomach. The majority of parietal acid forming cells are present in this segment. The fundus and the corpus function as the main reservoir of ingested food. The antrum extends from the lower border of the corpus to the pyloric sphincter. The majority of gastrin producing or G-cells are present in the antral mucosa. The main blood supply is variable but typically courses from the celiac axis into the gastric and gastroepiploic arcades. Nutrient vessels to the stomach coarse from the vascular arcades of the greater and lesser curvatures. These vessels penetrate the gastric wall in a perpendicular fashion and arborize horizontally in a dense vascular plexus throughout the wall of the stomach. For the most part, gastric innervation is provided by the vagus nerves which form a plexus around the esophagus and then reform into vagal trunks above the esophageal haitus. An extensive myenteric plexus is formed within the muscular wall of the stomach. Impulses from stretch or tension receptors within the gastric wall are transmitted to the nucleus tractus solitaris of the brain stem by afferent vagal fibers. These stretch/tension receptors within the fundus and corpus detect gastric distension or gastric pressure from ingested food. Recent studies appear to favor the role of gastric tension instead of gastric distension as the main elicitor of satiety. A smaller and less defined contribution is provided by sympathetic fibers from the celiac plexus. Within the submucosal layer, these fibers form Meissner""s plexus may regulate mucosal secretion and absorption.
The four basic components of the gastric wall are the mucosa, submucosa, muscularis and the serosa. These four components are found throughout the entire gastrointestinal tract. The mucosa consists of mucus secreting columnar epithelium that invaginates into glands. The cellular components of the glands vary within each segment of the stomach. The parietal or acid producing cells are mainly located within the gastric glands of the fundus and corpus. These exocrine cells also produce intrinsic factor that binds with vitamin B12 to facilitate absorption in the small intestine. Failure by the parietal cells to produce intrinsic factor leads to pernicious anemia, a condition commonly seen with atrophy of the gastric mucosa. The subjacent layer is frequently subdivided into the lamina propria, the muscularis mucosa and the submucosa. With the exception of the thin muscularis mucosa, this subjacent layer consists of collagen containing connective tissue. The next layer, the muscularis externa, consists of smooth muscle which propels food forward in the digestive tract. The muscularis is typically subdivided into two layers of circular and longitudinal fibers. An oblique layer of muscle fibers between the circular and longitudinal layers is typically present in the stomach. Auerbach""s myenteric plexus of parasympathetic fibers is contained within the muscularis externa. The fourth layer serosa is a dense outer covering of connective tissue that merges into the peritoneum.
Although subdivided into five anatomical segments, the physiological function of the stomach is described in two main components. The proximal third is termed the fundus which includes the corpus and fundus as a single functioning reservoir of ingested food. Smooth muscle cells of the physiological fundus have a lower resting potential that inhibits rapid depolarization and contraction. Instead, fundic muscle exhibits an active tone at rest that pushes ingested food into the antrum. The fundus also exhibits the phenomenon of receptive relaxation in which resting tone is decreased to accommodate the recently ingested bolus. The distal two-thirds of the stomach is termed the antrum which propels the partially digested food into the duodenum. Antral smooth muscle cells possess a higher resting potential that leads to rapid depolarization. Pacesetter potentials are initiated from the interstitial cells of Cajal that are located along the proximal aspect of the greater curvature. A wave of rapid depolarization is created within the antral smooth muscle that results in a type 2 peristaltic contraction. In contradistinction to the fundus, a resting tone is not exhibited in the antrum. The initiation of a fed pattern of gastric motility involves a complex interaction of locally released hormones with intrinsic and extrinsic neural pathways that are mediated through the vagus nerves.
A variety of non-invasive methods to study gastric motility evaluation are available although they include technical drawbacks and limitations. Contrast cinefluoroscopy with a barium meal has been used extensively for animal research but has limited application in humans due to exposure from ionizing radiation. Gastric intubation techniques can provide objective data on distensibility and motility with manometric/strain gauge transducers. Impedance epigastrography measures electrical patterns of gastric emptying. More recently, high resolution/real time ultrasonic imaging has provided a convenient non-invasive methodology to view gastric motility.
Currently a need exists for an efficacious minimally or non-invasive apparatus that is able to treat eating disorder related obesity. A further need exists for a non-invasive device that is able to reduce the distensibility and/or volume of the stomach. Still a further need exists for a non-invasive apparatus that is able to produce appetite suppression.
Accordingly, in view of the above presentation it is an immediate object of this invention to provide an apparatus and method for treating eating-disorder obesity that overcomes the deficiencies and omissions associated with the prior art.
Another object of the present invention is to provide an apparatus to treat the stomach and reduce the distensibility of the stomach.
Still another object of the invention is to provide an apparatus to treat the stomach and reduce the volume of the stomach.
Yet another object of the invention is to provide an apparatus to treat the stomach and produce appetite suppression.
Still yet another object of the invention is to treat the stomach without damaging a mucosal lining of the stomach.
Yet another object of the invention is to treat the stomach and produce a perception of stomach fullness with a reduced volume of food in the stomach.
These and other objects of the invention are achieved in an apparatus to modify a stomach wall comprises an elongated member including at least one lumen. A deployable member is coupled to the elongated member. The deployable member is configured to be advanceable and removable from the stomach in a non-deployed state and sized to be positioned in the stomach in a deployed state to engage at least portions of the stomach wall. The deployable member is further configured to house a fluidic media and at least portions of the deployable member wall is configured to be cooled by the fluidic media. The deployable member has a contour in the deployed state approximating at least a portion of a stomach. A microwave antenna is movably positioned in the deployable member so as to control a microwave field strength vector in relation to the antenna. The microwave antenna is configured to be coupled to a microwave energy source and deliver microwave energy to a selectable tissue site in the stomach wall while minimizing thermal injury to one of a mucosal or a submucosal layer. A cable member is coupled to the microwave antenna and is configured to be advancecable within the elongated member.
In another embodiment, the wound healing response is a circumferential wound healing response and includes deposition of scar collagen within the gastric wall.
In yet another embodiment, the energy delivery device is coupled to a cooling media. The cooling media cools a selected tissue site within the stomach wall to preserve the mucosal layers of the stomach during the delivery of energy from the energy delivery device.